I presume that there a distinction in the way that different Chirik's are pronounced if they are blended syllables ("Chaser") or not ("Malei"). If so...
How should the word Tzitzis ציצת be pronounced? If the word is צִיצִת, wouldn't the second chirik be pronounced as a shorter sound, as in the word "מִנְחָה" ? The word is always spelled צִיצִת throughout Tanach and not צִיצִית . (Although this former spelling would contradict Chazal's comment of the gematria of 600.)
I've heard from this site here: KOL HAMIKRA that both Chiriks are "Malei" and should be pronounced as a long Chirik sound.